Preparation of Molecular Sieving Activated Carbon Fiber from Pitch-Based Carbon Fiber

本工作的目的是开发一种以石油沥青基碳纤维为前驱体制备孔径均匀的多孔活性碳纤维(ACF)的工艺。显然，原料碳纤维直径较窄(约16微米)是阻碍现有碳活化技术应用于活性碳生产的主要因素之一。在混凝土中，我们能够证明，为了自由地控制和均匀地设计孔结构，同时满足增加比表面积和保持高产率的对抗性要求，有必要：(1)选择一种具有氧化能力的活化气，该活化气具有容易控制的氧化能力(二氧化碳)；(2)将活化气中的氧含量降低到低于约10%。(3)在活化处理过程中保持炉内均匀的温度分布。在预定温度(850,900,950ﾟC)下，在广泛的处理时间范围内研究了多孔活性碳纤维的比表面积与产率的关系。因此，我们制备了一系列具有分子筛分功能的活性炭样，它们的孔径大小不同，并能够评价其孔结构和吸附性能，从而：1)获得了高比表面积(2800m~2/g)的ACF，产率为42%；2)对烃类(甲烷、乙烯、正丁烷、异丁烷等)的气相吸附容量和速率。3)测定了氯仿和腐植酸在水相中的吸附容量和吸附速率。

The purpose of this work is to develop a process for the preparation of porous activated carbon fiber (ACF) with uniform pore size using petroleum-pitch-based carbon fiber as a precursor. It became clear that the narrow diameter (ca.16 mu m) of the raw material carbon fibers is one of the main factors preventing the application of existing carbon activation techniques to the production of activated carbon. In concrete, we were able to show that in order to freely control and design the pore structure uniformly whilst meeting the antagonistic requirements of both increasing the surface area and maintaining a high yield, it is necessary to : (1) select an activation gas that has an oxidizing ability which can be controlled with ease (carbon dioxide) ; (2) reduce the oxygen content of the activation gas to less than approx. 1 ppm ; (3) maintain a uniform temperature distribution in the furnace during activation treatment.The relationship between the specific surface area and the yield of porous activated carbon fiber was studied over a wide range of treatment time at predetermined temperatures (850,900,950 ﾟC). As a result, we were able to prepare a series of activated carbon samples with molecular sieving function differing from each other only in their pore size and were able to evaluate the pore structures and adsorption properties thus :1) ACF with a high surface area (2800 m^2/g) and a yield of 42% was obtained.2) Capacity and rate of gas phase adsorption of hydrocarbons (methane, ethylene, n-butane, iso-butane etc.) were measured and the character of the pore structures was investigated.3) Adsorption capacity and adsorption rate of chloroform and humic acid in aqueous phase were determined.